diff options
| -rw-r--r-- | compiler/rustc_middle/src/ty/layout.rs | 55 |
1 files changed, 19 insertions, 36 deletions
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs index 112f15c6f9e..00f53afd663 100644 --- a/compiler/rustc_middle/src/ty/layout.rs +++ b/compiler/rustc_middle/src/ty/layout.rs @@ -670,6 +670,23 @@ where }); } + let mk_dyn_vtable = || { + tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.mk_array(tcx.types.usize, 3)) + /* FIXME: use actual fn pointers + Warning: naively computing the number of entries in the + vtable by counting the methods on the trait + methods on + all parent traits does not work, because some methods can + be not object safe and thus excluded from the vtable. + Increase this counter if you tried to implement this but + failed to do it without duplicating a lot of code from + other places in the compiler: 2 + tcx.mk_tup(&[ + tcx.mk_array(tcx.types.usize, 3), + tcx.mk_array(Option<fn()>), + ]) + */ + }; + let metadata = if let Some(metadata_def_id) = tcx.lang_items().metadata_type() { let metadata = tcx.normalize_erasing_regions( cx.param_env(), @@ -684,48 +701,14 @@ where && Some(def.did()) == tcx.lang_items().dyn_metadata() && substs.type_at(0).is_trait() { - tcx.mk_imm_ref( - tcx.lifetimes.re_static, - tcx.mk_array(tcx.types.usize, 3), - ) - /* FIXME: use actual fn pointers - Warning: naively computing the number of entries in the - vtable by counting the methods on the trait + methods on - all parent traits does not work, because some methods can - be not object safe and thus excluded from the vtable. - Increase this counter if you tried to implement this but - failed to do it without duplicating a lot of code from - other places in the compiler: 2 - tcx.mk_tup(&[ - tcx.mk_array(tcx.types.usize, 3), - tcx.mk_array(Option<fn()>), - ]) - */ + mk_dyn_vtable() } else { metadata } } else { match tcx.struct_tail_erasing_lifetimes(pointee, cx.param_env()).kind() { ty::Slice(_) | ty::Str => tcx.types.usize, - ty::Dynamic(_, _, ty::Dyn) => { - tcx.mk_imm_ref( - tcx.lifetimes.re_static, - tcx.mk_array(tcx.types.usize, 3), - ) - /* FIXME: use actual fn pointers - Warning: naively computing the number of entries in the - vtable by counting the methods on the trait + methods on - all parent traits does not work, because some methods can - be not object safe and thus excluded from the vtable. - Increase this counter if you tried to implement this but - failed to do it without duplicating a lot of code from - other places in the compiler: 2 - tcx.mk_tup(&[ - tcx.mk_array(tcx.types.usize, 3), - tcx.mk_array(Option<fn()>), - ]) - */ - } + ty::Dynamic(_, _, ty::Dyn) => mk_dyn_vtable(), _ => bug!("TyAndLayout::field({:?}): not applicable", this), } }; |